Aerosolized drugs for inhalation are considered reasonable alternatives to injections or other types of drug-delivery systems, such as intravenous delivery, subcutaneous injection, and intramuscular. For example, insulin can be delivered by inhaling an aerosolized form, thus sparing a patient pain and inconvenience caused by subcutaneous injection of insulin.
Inhaling aerosols, however, typically lacks the accuracy of injections, and so is inappropriate for use in situations where accurate dosing is critical. With aerosolized drugs, the proper amount required for delivery is often not properly metered for delivery. For example, asthma inhalers typically have an acceptable accuracy of plus or minus 25% of the nominal dose. For systemic drug delivery of insulin, on the other hand, such a level of accuracy is considered too unpredictable to allow for appropriate use, even though aerosolized delivery is much less harmful to a patient than intravenous delivery.
Thus, a need exists for accurately and predictably delivering a predetermined dose of aerosolized drugs.